Abstract

A pulsar timing array (PTA) consists of an array of pulsars, widely distributed on the sky, with precise timing observations extending over many years for each pulsar. Such timing data sets have the potential to enable a direct detection of low-frequency gravitational waves and to establish an independent pulsar-based timescale. Three main PTAs currently exist, based in Europe, North America and Australia respectively. Data from the three PTAs are being combined to form an International Pulsar Timing Array (IPTA). These PTAs and recent results from them are described.